ALMA's sharpest view of IRAS 08544-4431: Unveiling the dust distribution asymmetries in the circumbinary disk
Abstract
The interactions between post-asymptotic giant branch (post-AGB) binaries and their circumbinary disks play a central role in shaping the evolution of these systems. Circumbinary disks around post-AGB binaries are stable, though relatively short-lived structures (104−105 years) and their physical properties and evolution remain poorly understood. In this study, we target IRAS 08544-4431, one of the best-studied post-AGB binaries. This system has well-constrained stellar and orbital parameters, exhibits well-defined characteristic refractory-depleted photospheric chemistry, and hosts a stable, sub-Keplerian circumbinary disk extending from a well-resolved sublimation rim at approximately 8 au to outer radii of approximately 1 000 au. We probe the disk layers close to the midplane using ALMA Band 7 continuum and 12CO J=3−2 observations of IRAS 08544-4431 obtained with baselines up to 16.2 km. These data provide the finest angular resolution yet achieved with ALMA for dust-continuum observations of post-AGB binaries with a (almost) face-on disk (15 au; 10 mas). The resulting map of dust continuum enabled resolving disk inner rim, a largely smooth radial profile, and a prominent azimuthal asymmetry at a radius of ∼45 mas. Notably, the location of this dust asymmetry coincides with the forward-scattering peak reported in SPHERE/VLT observations of IRAS 08544-4431. The 12CO emission is more extended than the dust continuum and confirms the disk rotation in this system. However, the global 12CO map shows indications of a spatial offset from the dust asymmetry, suggesting some degree of gas-dust decoupling. Together, these observations establish IRAS 08544-4431 as a key laboratory for studying disk and dust evolution in a parameter space distinct from that of young stars with protoplanetary disks.
Related
- The ALMA-QUARKS survey: A Keplerian Circumbinary Disk Candidate in the High-mass Star-forming Region IRAS 08303-4303
- Binary tidal evolution as a sculptor of circumbinary planet architectures
- Circumbinary discs as the origin of circumstellar material around interacting H-poor supernovae and fast blue optical transients
- Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks
- Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks
BibTeX
@misc{mohorian2026almas,
title = {{ALMA's sharpest view of IRAS 08544-4431: Unveiling the dust distribution asymmetries in the circumbinary disk}},
author = {Maksym Mohorian and Devika Kamath and Elizabeth Cappellazzo and Kateryna Andrych and Jacques Kluska and Hans van Winckel and Daniel Price and Toon De Prins and Arancha Castro-Carrizo and Javier Alcolea and Nicolas Cuello and Matthias Fabry and Valentin Bujarrabal},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.27997},
eprint = {2609.27997},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.27997},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - ALMA's sharpest view of IRAS 08544-4431: Unveiling the dust distribution asymmetries in the circumbinary disk
AU - Maksym Mohorian
AU - Devika Kamath
AU - Elizabeth Cappellazzo
AU - Kateryna Andrych
AU - Jacques Kluska
AU - Hans van Winckel
AU - Daniel Price
AU - Toon De Prins
AU - Arancha Castro-Carrizo
AU - Javier Alcolea
AU - Nicolas Cuello
AU - Matthias Fabry
AU - Valentin Bujarrabal
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.27997
UR - https://arxiv.org/abs/2609.27997
AB - The interactions between post-asymptotic giant branch (post-AGB) binaries and their circumbinary disks play a central role in shaping the evolution of these systems. Circumbinary disks around post-AGB binaries are stable, though relatively short-lived structures (10^4−10^5 years) and their physical properties and evolution remain poorly understood. In this study, we target IRAS 08544-4431, one of the best-studied post-AGB binaries. This system has well-constrained stellar and orbital parameters, exhibits well-defined characteristic refractory-depleted photospheric chemistry, and hosts a stable, sub-Keplerian circumbinary disk extending from a well-resolved sublimation rim at approximately 8 au to outer radii of approximately 1 000 au. We probe the disk layers close to the midplane using ALMA Band 7 continuum and ^12CO J=3−2 observations of IRAS 08544-4431 obtained with baselines up to 16.2 km. These data provide the finest angular resolution yet achieved with ALMA for dust-continuum observations of post-AGB binaries with a (almost) face-on disk (15 au; 10 mas). The resulting map of dust continuum enabled resolving disk inner rim, a largely smooth radial profile, and a prominent azimuthal asymmetry at a radius of ∼45 mas. Notably, the location of this dust asymmetry coincides with the forward-scattering peak reported in SPHERE/VLT observations of IRAS 08544-4431. The ^12CO emission is more extended than the dust continuum and confirms the disk rotation in this system. However, the global ^12CO map shows indications of a spatial offset from the dust asymmetry, suggesting some degree of gas-dust decoupling. Together, these observations establish IRAS 08544-4431 as a key laboratory for studying disk and dust evolution in a parameter space distinct from that of young stars with protoplanetary disks.
ER -